I couldn't believe it when I asked their addresses.

Turns out, they lived just down the street from me in Mount Pleasant, Michigan in the United States.

But I'd just met them in Beijing.

I'd just arrived in China in 2005 to intern for China Daily.

I was assigned to cover an interpretive dance performance created to honor American missionary Minnie Vautrin (1886-1941), who risked her life to save 10,000 Chinese women during the Nanjing Massacre.

The show's organizers had invited some of her living relatives to attend the rehearsal.

I ended my interview with them by confirming their cities of residence. They not only lived a few houses down from me in Mount Pleasant but also worked as administrators at the university I was attending.

We were astounded by the coincidence. We agreed to meet up in Michigan but never got around to it.

I'd never heard of Vautrin before arriving in China. But I immediately came to understand why she's hailed as a hero in China.

The missionary and educator, who's known in China as the "Goddess of Mercy", first arrived in China in 1912 and later became dean of the Nanking Jinling Women's College. She repelled Japanese invaders from the school in 1937, during the six-week siege in which 300,000 unarmed Chinese were killed and more than 20,000 women were raped.

Vautrin personally patrolled the school to fend off any attempts to attack the women inside.

She declared: "Whoever wants to go through this gate will have to do so over my dead body." And she meant it.

However, largely because of the horror she experienced during that time, she committed suicide soon after returning to the US following a nervous breakdown.

It turns out that she was also buried in the same county in which I lived and attended university. I also planned to visit her grave but, again, never got around to it.

These incredible coincidences indeed seemed to point to the truth of the old adage, "It's a small world after all".

That said, I was again absolutely shocked by another unlikely encounter about two weeks after I returned to Beijing in 2006.

I was sitting outside a bar on the main street of the capital's Sanlitun area when I heard a conspicuously surprised voice say, "Erik?"

I turned around and was astonished to see a fellow member of my high school newspaper's editorial board.

I hadn't seen Brady in about half a decade, since I'd moved away from Midland, Michigan, which borders Mount Pleasant.

And I had to study his face for some time to make sure I really was looking at who I thought I was looking at. I was.

It happened that Brady was doing a short study-abroad program at the university across from my workplace.

I didn't have Facebook back then. But we've since connected on the platform.

Indeed, it's not only a small world after all, but it's also getting smaller, especially as such connecting technologies as social media advance.

Through Facebook, I came to learn I have distant relatives from Sweden who live in Shanghai. I've considered contacting them but haven't yet.

We've all heard of the theory of "six degrees of separation", also known as "six handshakes", which suggests every human is linked by six or fewer social connections. That is, friends of friends of friends…

However, this concept, which began in academia and later leaked into popular culture, is largely regarded as an urban legend. Empirical studies supporting the idea have been conducted but also criticized for their methodologies.

Either way, as the world shrinks and China's prominence continues to rise, I expect to encounter more unlikely encounters, especially in Beijing.

Contact the writer at erik_nilsson@chinadaily.com.cn